1. Field of the Invention
The present invention relates to a communication device in which data transmission between a modem and a controller is performed on the basis of interrupt processing.
2. Description of the Related Art
In conventional communication devices of this type, such as a facsimile device, interrupt processing is performed in a fixed manner in the operation of receiving procedural signals and image signals. That is, a modem generates an interrupt to a CPU (controller) each time the modem has received one byte of data.
In recent years, the recommendation V.34 has been accepted widely, and the transmission speed has become as high as 28.8 kb/s. In such a high speed operation, however, if an interrupt is generated each time one byte of data is received, the interrupt request can make it impossible for the device to operate correctly at the required speed. To avoid the above problem, it has been recommended that an interrupt be generated each time a plurality of bytes of data have been received. However, the details of the method of controlling the interrupt processing are not defined in the recommendation.